In-ear monitors (IEMs), which are also known as in-ear headphones, canalphones, and in-ear buds, are electronic devices that include at least one electroacoustic transducer, which converts an input electrical signal supplied to the IEMs into a corresponding audio output. A portion of each IEM is inserted into a user's ear canal and physically interfaces with and seals against the user's ear canal walls to provide a path for the audio output generated by the IEM to the user's ear drum.
Some IEMs are custom fit for a user and adapted to the user's unique ear canal size and shape. However, custom IEMs are expensive and only adapted for a single user. Other IEMs are generic and include a single ear plug (or resilient membrane tip) size and shape that is intended to substantially resiliently deform and subsequently expand to fit multiple ear canal sizes and shapes. However, the lack of adjustability of these generic IEMs prevent their performance from being adequate for all users in all situations.
Other generic IEMs include an array of removable resilient ear plugs (or resilient membrane tips) to adapt the generic IEMs for multiple ear canal sizes and shapes. For these types of IEMs, the user chooses the resilient ear plugs that best match the user's ear canal by trying different ear plugs and selecting the one that provide the best perceived seal, level of comfort, and/or secure fitment. These sorts of generic IEMs may suffer from a limited range of resilient ear plugs that may not adequately fit each user, and the user may prefer different ear plugs for different purposes (e.g., the user's interest in secure fitment may be higher when exercising and lower when relaxing).